Revert "Revert "audioflinger: implement silenced capture for mmap""

This reverts commit 611ebb95e76c230214780b7b583b8a3c5277ac7a.

Bug: 78118584
bug: 72134552
Test: 'adb shell write_sine_callback -m3 -pl -s100 -x' and Plug headphones in and out.
Test: AAudio CTS tests
Change-Id: I7558ad7b9c6c2d352ebce105382fe914c26fd35e
9 files changed